Shape transitions and ground-state properties of tungsten isotopes in covariant density functional theory

TL;DR

This paper explores the shape evolution and stability of tungsten isotopes across a wide neutron range using covariant density functional theory, revealing shape coexistence, subshell closures, and predicting the neutron drip line.

Contribution

It provides a comprehensive analysis of tungsten isotopes' structural properties with multiple relativistic functionals, identifying shape transitions and a new subshell closure at N=118.

Findings

Shape coexistence observed in specific isotopes.

Predicted neutron drip line at N=184.

Identification of a subshell closure at N=118.

Abstract

This study investigates the structural evolution of even-even tungsten isotopes ($^{154\text{--}264}$W) using covariant density functional theory (CDFT) with four relativistic functionals: DD-ME1, DD-ME2, DD-PC1, and DD-PCX. Key nuclear properties, including binding energies, quadrupole deformation parameters, two-neutron separation energies, neutron pairing energies, nuclear radii, and potential energy curves, are analyzed to explore shape transitions and stability from neutron-deficient to neutron-rich isotopes up to the drip line. The results reveal a dynamic shape evolution, with spherical configurations at $N = 82$ and $N = 126$, prolate dominance in intermediate regions, and shape coexistence in isotopes such as $^{158}$W, $^{160}$W, $^{194}$W, $^{196}$W, $^{206}$W, and near $^{244\text{--}248}$W. A potential subshell closure at $N = 118$ is identified, supported by anomalies in separation energies and vanishing pairing energies. The neutron drip line is predicted at $N = 184$, marked by a return to spherical symmetry. Comparisons with experimental data and other theoretical models, including the deformed Hartree-Fock-Bogoliubov method with the Skyrme SLy4 interaction, the Finite Range Droplet Model, and the Relativistic Mean Field model with NL3, show strong agreement, validating the robustness of CDFT. These findings enhance our understanding of nuclear structure in the medium-to-heavy mass region and provide insights relevant to r-process nucleosynthesis, thereby guiding future experimental studies at radioactive ion beam facilities.